ML-DS 2006 protocol compared with the historical control arm (AML-BFM 98). Scheme of the different study protocols as indicated. ML-DS 2006: AIE (cytarabine 100 mg/m² per day [days 1-2] and 100 mg/m² per 12 hours [days 3-8], idarubicin 8 mg/m² per day [days 3, 5, and 7], and etoposide 150 mg/m² per day [days 6-8]); AI (cytarabine 500 mg/m² per day [days 1-4] and idarubicin 5 mg/m² per day [days 3 and 5]); haM (cytarabine 1 g/m² per 12 hours [days 1-3] and mitoxantrone 7 mg/m² per day [days 3-4]); HA (high-dose cytarabine 3 g/m² per 12 hours [days 1-3]). The cumulative doses were 27 400 mg/m² cytarabine, 450 mg/m² etoposide, 34 mg/m² idarubicin, and 14 mg/m² mitoxantrone. Chemotherapy for children younger than 12 months of age, or weighing <12 kg, was calculated based on body weight. In addition, patients received cytarabine intrathecally at the start of each treatment block (4 doses in total, 20-40 mg per dose adapted to age) as a CNS prophylaxis. AML-BFM 98 (reduced-intensity arm for children with ML-DS; historical control arm): AIE (cytarabine 100 mg/m² per day [days 1-2] and 100 mg/m² per 12 hours [days 3-8], idarubicin 8 mg/m² per day [days 3, 5, and 7] and etoposide 150 mg/m² per day [days 6-8]); AI (cytarabine 500 mg/m² per day [days 1-4] and idarubicin 5 mg/m² per day [days 3 and 5]); haM (cytarabine 1 g/m² per 12 hours [days 1-3] and mitoxantrone 7 mg/m² per day [days 3-4]); HAE (high-dose cytarabine 3 g/m² per 12 hours [days 1-3] and etoposide 125 mg/m² per day [days 2-5]). Maintenance therapy until 1.5 years after start of induction therapy was thioguanine daily 40 mg/m² per os (p.o.) and cytarabine 40 mg/m² subcutaneously (s.c.) every 4 weeks on 4 consecutive days. The cumulative doses were ∼29 400 mg/m² cytarabine, 950 mg/m² etoposide, 34 mg/m² idarubicin, and 14 mg/m² mitoxantrone.